Dry eye disease is a general term for a variety of conditions characterized by abnormalities in the tear film, where nearly half (48%) of Americans age 18 and older regularly experience dry eye symptoms. Dry eye is characterized by symptoms such as feeling that grit or some other object or material is in the eye, burning sensation, sore eyes, itchy eyes, aching sensations, heavy eyes, fatigued eyes, dryness sensation, red eyes, photophobia and blurred vision. Further the term “dry eye” syndrome is commonly used to refer to the ophthalmic condition resulting from the reduction or the instability of the tear film while, more properly, the typical alterations of the corneal surface occurring in this connection are referred to by the term “keratoconjunctivitis sicca”.
The tear film consists of an inner mucous layer, a middle aqueous layer which forms the bulk of the tear film, and an outer lipid layer. The aqueous layer is secreted by the lacrimal glands and the accessory lacrimal glands, and the tear fluid is drained by the efferent tear ducts. While the underlying causes of dry eye diseases are largely unknown, it is generally accepted that they are associated with abnormalities in the meibomian glands (which secrete the lipid layer), and abnormalities in drainage through the efferent tear duct passage, changes in mucin composition and mucous viscosity may also affect tear flow.
Until recently, the methods used for the treatment of dry eye disease were topical administration of over-the-counter compositions that serve as artificial tears (such as Refresh® marketed by Allergan), ophthalmic product containing cyclosporine A (Restasis® marketed by Allergan), ophthalmic product containing lifitegrast (Xiidra® marketed by shire), or surgery to close efferent drainage.
Therefore, there is a scope in developing new formulations in this area which are less toxic and more biocompatible with more emphasis on biomimetic approach in treatment of dry eye disease.